Examination of insulation displacement connection

ABSTRACT

A CCD laser displacement gauge  9  is movable in three directions, that is, a vertical direction and two directions perpendicular to each other in a horizontal plane, and this gauge can be moved to a insulation displacement connecting center so as to detect a insulation displacement connecting height, the presence/absence of a wire, abnormal insulation displacement connection and a wire projecting amount. The insulation displacement connecting height, the wire presence/absence and the abnormal insulation displacement connection are detected by measuring a height of an upper surface of a wire sheath from a reference position at the position of the slot (at a middle position between two terminals if these terminals are juxtaposed) Whether or not the wire projecting amount is proper is determined by detecting the presence/absence of the wire at a position obtained by subtracting an absolute value of a tolerance from a normal projecting position. In the measurement, a waveform of a laser beam is sampled, and its peak is used as a measurement result. The CCD system detects the amount of light for each picture element, and even if there are variations in the surface condition of the wire which has just been insulation-displacement-connected, the position where the light amount is at a peak can be accurately detected.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a method of examining insulationdisplacement connection, for example, in the production of a wireharness, and also relates to an apparatus for performing this method.

[0003] 2. Description of the Related Art

[0004] As shown in FIG. 7, a wire harness, for example, comprisesparallel wires 50 each having a conductor 51 coated with an insulatingresin 52, connectors 30 connected to the wires 50 at suitable regions ina lengthwise direction and a widthwise direction, and covers 31 attachedto the respective connectors 30 if necessary. In view of the efficiencyof the operation, insulation displacement fitting connection(hereinafter referred to as “insulation displacement connection”) asshown in FIG. 8 has now been increasingly used for connecting the wires50 to the connector 30.

[0005] As shown in FIG. 8, in this insulation displacement connection, avertically-movable, insulation displacement connecting blade holder (notshown), having insulation displacement connecting blades 10corresponding respectively to the wires 50, is moved downward, and adistal end surface of each insulation displacement connecting blade 10press-fits the associated wire 50 into slots 41 a of an associatedinsulation displacement connecting terminal 40 of the connector 30, sothat the wire is held in the terminal 40 by spring back, produced in theterminal 40 at this time, and hence is connected to the terminal. Duringthis press-fitting operation, the insulating sheath 52 is cut by inneredges of the slots 41 a, so that the conductor 51 in the insulatingsheath 52 is brought into contact with the inner edges of the slots 41a, thereby making an electrical connection between the conductor 51 andthe insulation displacement connecting terminal 40.

[0006] Examples of defective insulation displacement connection,developing during the above insulation displacement connectingoperation, are as follows.

[0007] For some reason, if any of the wires, fed to the insulationdisplacement connecting step, is inserted in a twisted condition intothe slots to be insulation-displacement-connected to the terminal, thewire can be press-fitted excessively or inadequately. Also, there is apossibility that the wire fails to be inserted into the slots, and theempty hitting occurs, so that a wire-absent condition develops.Alternatively, there can be encountered abnormal insulation displacementconnection in which the wire to be inserted into the adjoining cavity isinserted, together with the proper wire, into one slot, so that thedouble wire-hitting occurs.

[0008] In the conventional insulation displacement connectionexamination, it is judged that the insulation displacement connection isfinished when the insulation displacement connecting blade forpress-fitting the wire into the slots, reaches its lower dead point.With this method, however, the above deficiencies can not be detected.

[0009] For example, in the case of “wire absence”, the insulationdisplacement connecting blade reaches the lower dead point withoutundergoing any resistance, and even in the case of the abnormalinsulation displacement connection (double wire-hitting), the insulationdisplacement connecting condition is not different from the properinsulation displacement connecting condition for one wire if the wiresare soft, and if the force for pressing the insulation displacementconnecting blade is extremely large.

SUMMARY OF THE INVENTION

[0010] It is therefore an object of this invention to provide a methodof examining defective insulation displacement connection developingduring the insulation displacement connecting operation, and also toprovide an apparatus for performing this method.

[0011] In the present invention, in order to solve the above problems,by measuring a height of an upper surface of the insulation displacementconnected wire from a reference position, the examination of theinsulation displacement connection is effected. With this method, thepresence of the wire can be directly detected, and therefore informationof the insulation displacement connecting height, the wirepresence/absence, the abnormal insulation displacement connection andthe wire projecting amount, which represent the insulation displacementconnected condition, can be obtained.

[0012] “The insulation displacement connecting height” is the height ofthe upper surface of the wire sheath from the reference position at theposition of the slot. The reference position in the direction of theheight may be any arbitrary position in the space, and can be, forexample, an upper surface of a connector-positioning pallet (the bottomsurface of the connector).

[0013] In the case where the connector (not shown) is of such a designthat two terminals 41 are juxtaposed and spaced a distance D₁ from eachother in the direction of the length of the wire 50 so that the wire canbe insulation-displacement-connected at two portions thereof as shown inFIG. 5, the measurement position in the horizontal direction is a middleposition A₁ between the two terminals 41 and 41. In the case where onlyone terminal 41 is attached to the wire 50 in the direction of thelength of the wire, the measurement position in the horizontal directionis a position A₂ at which this terminal 41 exists.

[0014] With respect to “the wire presence/absence”, if the wire ispresent, it is necessarily detected in the measurement of the wireinsulation displacement connecting height. If the wire is absent, itdetected when the height of the wire sheath from the reference position,measured in this measurement, represents a value smaller than its normalvalue by an amount equal to the normal outer diameter of the wire. “Theabnormal insulation displacement connection” is encountered, forexample, if a plurality of wires are insulation-displacement-connectedin a bundled manner into one slot, and in this case, the position of thesheath of the uppermost wire is measured, and therefore the measuredvalue of the above insulation displacement connecting height isextraordinarily large, and therefore it is judged that this is theabnormal insulation displacement connection.

[0015] Although “the wire projecting amount” is the amount of projectingof the wire from the side surface of the terminal, this amount itself isnot measured, and as shown in FIG. 5, a position B, obtained bysubtracting an absolute value d of a tolerance from a normal projectingposition (that is, a position advanced a normal projecting amount D₂from the side surface of the terminal 41 in the direction of projectingof the wire 50), is defined as an examination position, and at thisposition B, the presence/absence of the wire 50 is detected according tothe same procedure as described above for the examination of “the wirepresence/absence”, and the judgment is made based on this. Morespecifically, if the presence of the wire 50 at the examination positionB is confirmed, it is decided that the projecting amount is normal, andif it is judged that the wire 50 is absent, it is decided that theprojecting amount is not normal.

[0016] If not less than two of the wire insulation displacementconnecting height, the wire projecting amount, the wire presence/absenceand the abnormal wire insulation displacement connection are measured,the defective insulation displacement connection can be detectedmultilaterally, and the product of a high quality can be obtained.

[0017] In order to effect the above examination, there is used theapparatus provided with the CCD laser displacement gauge movable in thedirection of juxtaposition of the wires.

[0018] In this apparatus, the CCD laser displacement gauge is scanninglymoved in the direction of juxtaposition of the wires so that themeasurements in the above Items can be made.

[0019] The reasons why the laser displacement gauge is used are that itis not desirable to apply a load to the wire at the insulationdisplacement connecting position and that not a contact-type (whichapplies a load) but a non-contact-type measurement instrument need to beused. The reasons why the CCD system is used are that the amount oflight for each picture element can be detected and that even if thelight amount varies depending on the surface condition of the object tobe measured, the position where the light amount is at a peak can beaccurately detected.

[0020] In the insulation displacement connecting position, theinsulation displacement connected wire is pressed by the insulationdisplacement connecting blade, and also receives forces from the inneredges of the slot, so that the surface of the wire is not flat, andtherefore the function of the CCD system is needed.

[0021] Although various colors and patterns are used for the sheath ofthe wires of the wire harness, the CCD laser system is not influenced bythese elements.

[0022] The present disclosure relates to the subject matter contained inJapanese patent application No. Hei. 11-13304 (filed on Jan. 21, 1999)which is expressly incorporated herein by reference in its entirely.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 a perspective view of a preferred embodiment of a movingmechanism of the invention.

[0024]FIG. 2 is a side-elevational view of the embodiment.

[0025]FIG. 3 is a rear view of the embodiment.

[0026]FIG. 4 is a plan view of the embodiment.

[0027]FIG. 5 is a perspective view showing a measurement position.

[0028]FIG. 6 is a diagram showing a control construction.

[0029]FIG. 7 is a perspective view showing an example of a wire harness.

[0030]FIG. 6 is a perspective view showing insulation displacementconnection.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] A preferred embodiment of the present invention will now bedescribed with reference to the drawings. An examination apparatus ofthis embodiment is incorporated in an area of a insulation displacementconnecting process, and a moving mechanism for moving a CCD laserdisplacement gauge for effecting measurements for examination purposesis provided in the vicinity of a insulation displacement connectingmachine.

[0032] The moving mechanism 10, shown in FIGS. 1 to 4, effects movementsin three directions (that is, a vertical direction and two directionsperpendicular to each other in a horizontal plane) so as to move the CCDlaser displacement gauge 9 from a predetermined stand-by position to ameasurement position (insulation displacement connecting center), andthis moving mechanism 10 is supported on two vertically-extending, posts11 and 12.

[0033] A guide plate 2 for a slider 1 for horizontally moving the CCDlaser displacement gauge 9 extends horizontally between the two posts 11and 12. A guide grooves 2 a for guiding the slider 1 is formed in alongitudinal side surface of the plate 2, and the slider 1 is coupled tothe guide groove 2 a, and is driven by a servo motor (not shown). Thedirection (horizontal direction) of movement of the slider 1 is parallelto a direction of juxtaposition of cavities V in a connector C, that is,a direction of juxtaposition of wires to beinsulation-displacement-connected to respective terminals (i.e., adirection of the width of the connector C). Slits plates 3 are mountedon an upper surface of the slider 1, and photo-microsensors 4 forprojecting light onto the slit plates 3 so as to detect the movement ofthe slider 1 are mounted on an upper surface of the guide plate 2.

[0034] An air cylinder 5 for vertically moving the CCD laserdisplacement gauge 9 is mounted on the slider 1 through a bracket 1 a.

[0035] An air cylinder 6 for moving the CCD laser displacement gauge 9in a horizontal direction perpendicular to the direction of horizontalmovement of the slider 1 is mounted on a moving portion 5 a of the aircylinder 5 through a bracket 7.

[0036] A bracket 8 for mounting the CCD laser displacement gauge 9thereon is mounted on a moving portion 6 a of the air cylinder 6 througha cylinder 8 a, and the CCD laser displacement gauge 9 is mounted on oneside of a lower end portion of this bracket 8. When the projectingamount is to be measured, the cylinder 8 a moves the bracket 8 in adirection of arrow 9 a (FIG. 1) so as to move the CCD laser displacementgauge 9 to the projecting amount examination position disposed forwardlyof the insulation displacement connecting height examination position.

[0037] With the apparatus of the above construction, the CCD laserdisplacement gauge 9 can be moved in the three directions (that is, thevertical direction and the two directions perpendicular to each other inthe horizontal plane) to approach from the predetermined stand-byposition to the measurement position.

[0038] In this embodiment, the measurements in the following four Itemsare made by the use of the above apparatus, thereby effecting theinsulation displacement connection examination.

[0039] (1) Insulation displacement connecting height

[0040] (2) Present/absence of the wire

[0041] (3) Abnormal insulation displacement connection

[0042] (4) Wire projecting amount

[0043] The methods for measuring these are as described above. Althoughthe reference position in the direction of the height may be anyarbitrary position in the space, this reference position in thisembodiment is the upper surface of the connector C.

[0044] In the case where the connector (not shown) is of such a designthat two terminals 41 are juxtaposed and spaced a distance D₁ from eachother in the direction of the length of the wire 50 so that the wire canbe insulation-displacement-connected at two portions thereof as shown inFIG. 5, the measurement position in the horizontal direction withrespect to the above Items (1) to (3) is a middle position Al betweenthe two terminals 41 and 41. In the case where only one terminal 41 isattached to the wire 50 in the direction of the length of the wire, themeasurement position in the horizontal direction is a position A₂ atwhich this terminal 41 exists.

[0045] As described above, in the measurement of “the wire projectingamount” of the above Item (4), at a position B, obtained by subtractingan absolute value d of a tolerance from a normal projecting position(that is, a position advanced a normal projecting amount D₂ from theside surface of the terminal 41 in the direction of projecting of thewire 50 as shown in FIG. 5), the presence/absence of the wire 50 isdetected according to the same procedure as described above for theexamination of “the wire presence/absence” of the above Item (2), andthe judgment is made based on this. More specifically, if the presenceof the wire 50 at the examination position B is confirmed, it is decidedthat the projecting amount is normal, and if it is judged that the wire50 is absent, it is decided that the projecting amount is not normal.

[0046] In this embodiment, the examination is conducted for eachinsulation displacement connecting operation, that is, for eachconnector C of the wire harness. Therefore, in the above-mentionedmeasurement position, the CCD laser displacement gauge 9 is scanninglymoved in the direction of juxtaposition of the wires 50. The slider 1effects this horizontal movement, and as described above, the slitplates 3 are fixedly mounted on the slider 1, and the photo-microsensors4 are mounted on the upper surface of the guide plate 2 along which theslider 1 slides. The photo-microsensors 4 project light during theexamination process, and when the slider 1 slides, the light isintercepted by the slit plates 3, mounted on the slider 1, and passesthrough slits 3 a in these slit plates. These are used as timingsignals, and the timing of measurement for each cavity V is determined.The timing of the examination is a time period from a leading edge ofthis signal to a leading edge of the next signal, and during this timeperiod, the examination of the insulation displacement connection of thewire 50 in one cavity V is effected. Namely, the slits 3 a in the slitplates 3 a correspond to the cavities V, respectively.

[0047] In the measurement, a waveform of the laser beam is sampledduring the measurement period, and its peak is used as a measurementresult. The reasons why the CCD system is used are that the amount oflight for each picture element can be detected and that even if thereare variations in the surface condition of the wire 50 which has justbeen insulation-displacement-connected at the insulation displacementconnecting position, and therefore is pressed by the insulationdisplacement connecting blade, and also receives forces from the inneredges of the slot 41 a, so that the wire 50 is deformed, the positionwhere the light amount is at a peak can be accurately detected.

[0048] As shown in FIG. 6, with respect to the construction of thecontrol, the start and end of the measurement are transmitted to asequencer 22 via a graphic controller 21 on the basis of the timingsignal T produced by the combination of the photo-microsensors 4 and theslit plates 3, and a measurement instruction is fed from the sequencer22 to the CCD laser displacement gauge 9.

[0049] The sequencer 22 instructs the slider 1 and the two cylinders 5and 6 to move the CCD laser displacement gauge 9 to the insulationdisplacement connecting position, and further instructs the slider 1 tomove the CCD laser displacement gauge 9, disposed at this insulationdisplacement connecting position, in the direction of juxtaposition ofthe wires 50 for scanning purposes, and further instructs the cylinder 8a (which serves to move the CCD laser displacement gauge 9 to theprojecting amount examination position disposed forwardly of theinsulation displacement connecting height examination position) to movethe bracket 8, having the CCD laser displacement gauge 9 mountedthereon, in the direction of the arrow 9 a when the projecting amount isto be measured.

[0050] When the number of cavities is changed depending on the type ofthe connector to be used, and when the number of the insulationdisplacement connections of the wires and the insulation displacementconnecting positions are changed even if the number of the cavities arethe same, data, related to the corresponding specification, arebeforehand programmed in the sequencer 22 and the graphic controller 21,and the control is effected.

[0051] With respect to the measurement results, the measurement resultwithin the tolerance is indicated as “Go”, the measurement result largerthan the upper limit of the tolerance is indicated as “H”, and themeasurement result smaller than the lower limit of the tolerance isindicated as “L”.

[0052] With respect to those products, judged defective in theexamination, the cover is attached to the connector C after theinsulation displacement connecting process, thereby providing thefinished product, and thereafter such defective products are separatedfrom the good products, and are discarded.

[0053] As described above, in the present invention, by measuring theheight of the upper surface of the sheath of the insulation displacementconnected wire from the reference position, the examination of theinsulation displacement connection is effected, and therefore thepresence of the wire can be directly detected, and the examination canbe carried out positively.

[0054] With this examination method, the examinations of “the insulationdisplacement connecting height”, “the wire presence/absence”, “theabnormal insulation displacement connection” and “the wire projectingamount” can be conducted. “The insulation displacement connectingheight” is the height of the upper surface of the wire sheath from thereference position at the position of the slot.

[0055] With respect to “the wire presence/absence”, if the wire ispresent, it is necessarily detected in the measurement of the wireinsulation displacement connecting height. If the wire is absent, itdetected when the height of the wire sheath from the reference position,measured in this measurement, represents a value smaller than its normalvalue by an amount equal to the normal outer diameter of the wire.

[0056] When the measured value of the insulation displacement connectingheight is extraordinarily large, this indicates “the abnormal insulationdisplacement connection”.

[0057] Although “the wire projecting amount” is the amount of projectingof the wire from the side surface of the terminal, this amount itself isnot measured, and the position, obtained by subtracting an absolutevalue of a tolerance from the normal projecting position (that is, theposition advanced a normal projecting amount from the side surface ofthe terminal in the direction of projecting of the wire), is defined asan examination position, and at this position, the presence/absence ofthe wire is detected according to the same procedure as described forthe examination of “the wire presence/absence”. More specifically, ifthe presence of the wire at this examination position is confirmed, itis decided that the projecting amount is normal, and if it is judgedthat the wire is absent, it is decided that the projecting amount is notnormal.

[0058] If not less than two of the wire insulation displacementconnecting height, the wire projecting amount, the wire presence/absenceand the abnormal wire insulation displacement connection are measured,the defective insulation displacement connection can be detectedmultilaterally, and the product of a high quality can be obtained.

[0059] If the CCD laser displacement gauge is used for effecting theabove examination, the measurement can be effected in non-contactrelation to the wires to be measured, and therefore a force will not beapplied to the insulation displacement connected portion of the wire,thus eliminating a possibility that this portion is damaged. Andbesides, since the high-speed sampling can be effected, the measurementcan be carried out during the operation, and therefore the operationrate will not be much decreased.

What is claimed is:
 1. A method of examining insulation displacementconnection in which wire are insulation-displacement-connected to slotsin a plurality of juxtaposed terminals, comprising the steps of:measuring a height of an upper surface of said wire from a referenceposition, and judging whether or not the insulation displacementconnecting position is normal.
 2. A method of examining insulationdisplacement connection as claimed in claim 1, in which not less thantwo of the wire insulation displacement connecting height, a wireprojecting amount, wire presence/absence and abnormal wire insulationdisplacement connection are measured, using said examination method. 3.An apparatus for conducting examining insulation displacement connectionof a plurality of juxtaposed terminals comprising: a CCD laserdisplacement gauge which is movable in a direction of juxtaposition ofsaid terminals, two posts extending vertically, a guide plate for aslider for horizontally moving said CCD laser displacement gauge, whichextends horizontally between said two posts, a guide grooves for guidingsaid slider which is formed in a longitudinal side surface of said guideplate, and which is coupled to said guide groove, slits plates which aremounted on an upper surface of said slider, photo-microsensors forprojecting light onto said slits plate in order to detect a movement ofsaid slider, which are mounted on an upper surface of said guide plate,two air cylinders for vertically and horizontally moving said CCD laserdisplacement gauge, one air cylinder is mounted on said slider through abracket so as to move in a vertical direction and the other air cylinderis mounted on a moving portion of said one air cylinder through abracket so as to move in a horizontal direction perpendicular to thedirection of horizontal movement of said slider.